Advances in plant breeding have resulted in a 73% increase in the iron content of black bean varieties similar to those consumed in Mexico. The efficacy of consuming these biofortified beans was tested in 587 primary school children in the Mexican state of Oaxaca. We randomized 20 schools to consume either biofortified (95mg/kg Fe) or control beans (55mg/kg Fe) for 110 days. At baseline 137 children (24%) were iron depleted with serum ferritin <20μg/L, and 18% were anemic (Hb<110g/L). Children consumed an average of 11 kg beans during the trial and the high iron bean group consumed an estimated additional 18% of their RI for iron. Children in the high iron bean group had significantly greater reduction in transferrin receptor (TfR) from baseline to end line compared to the low iron group (p<.001). The more iron deficient subjects (high baseline TfR) experience the greatest group difference in change of TfR (p=.05) compared to subjects with lower baseline TfR (interaction of baseline TfR by bean group, p=.011). The greatest group difference in improvement in TfR was also seen in children who consumed the most beans throughout the feeding trial. Interpretation of change in ferritin values appears to be complicated by differential rates of infections in the 2 groups. We conclude that consuming beans that are bred for enhanced iron content improves selected measures of iron status in school children. Supported by HarvestPlus